✍ Scribed by Donald T. Sawyer
No coin nor oath required. For personal study only.
The interaction of reduced transition-metal porphyrins [e.g. PMn (II), PFe (II), PCo (II)] with oxygen species (· O ~2~·, H ~2~^+^ O ·/ HO ·, HOO ·, · O ·) involves radical/radical coupling to form covalent bonds. Coordinately unsaturated iron(II) porphyrins form two sigma bonds with · O ~2~·(-Δ G ~BF~ = 1–6 kcal mol ^-1^) via two of the four unpaired d-electrons of the iron center. The hydroxyl radical [Formula: see text] couples with an unpaired electron of the PM (II) porphyrins to form a single covalent bond [[Formula: see text], PM ^III^– OH ]. The bond energies (-Δ G ~BF~ ) for [Formula: see text] and [Formula: see text] are 65 ± 4 and 58 kcal mol^-1^, respectively. Under neutral conditions the uncharged species [( Cl ~8~ TPP ) Mn ^III^– OH , ( Cl ~8~ TPP ) Fe ^III^– OH , (Cl~8~TPP)Co^III^- OH ] have bond-formation energies (-Δ G ~BF~ ) of 70 ± 4, 63, and 61 kcal mol^-1^, respectively. In acetonitrile solutions atomic oxygen (· O ·; derived from ozone, O ~3~) couples with ( Cl ~8~ TPP ) Mn ^III^[ ClO ~4~], ( Cl ~8~ TPP ) Mn ^II^, ( Cl ~8~ TPP ) Fe ^III^[ ClO ~4~], and ( Cl ~8~ TPP ) Fe ^II^ to form ( Cl ~8~ TPP ^+^) Mn ^V^ O (-ΔG ~BF~ = 59 ± 4 kcal mol ^-1^), ( Cl ~8~ TPP ) Mn ^IV^= O (85 kcal mol ^-1^), ( Cl ~8~ TPP ^+^·) Fe ^IV^= O (68 kcal mol ^-1^; model for compound I of horseradish peroxidase), and ( Cl ~8~ TPP ) Fe ^IV^= O (78 kcal mol ^-1^; model for compound II of horseradish peroxidase). The weakly bonded species [( Cl ~8~ TPP ^+^) Mn ^V^= O and ( Cl ~8~ TPP ^+^·) Fe ^IV^= O ] epoxidize olefins with near-stoichiometric efficiency; the other two species are essentially unreactive with olefins.
📜 SIMILAR VOLUMES
## Abstract The kinetics of the H~2~O~2~ decomposition by Cu(II)‐, Co(II)‐, and Fe(III)‐amine complexes supported on the surface of silica‐alumina (25% Al~2~O~3~) catalyst have been investigated. The decomposition process proceeded with first‐order kinetics for the substrate concentration. With cop
Metal [Fe(II), Cu(I), Co(II), Mn(III)]/Hydroperoxide-Induced Activation of Dioxygen (•O 2 •) for the Ketonization of Hydrocarbons: Oxygenated Fenton Chemistry -[25 refs.]. -(SAWYER, D. T.;
New 1D complexes are obtained from the reaction of 1,1Јbiphenyl-2,2Ј-dicarboxylic acid (diphenic acid) with KOH and [ under hydrothermal conditions. Compounds 1 and 2 are isostructural and their structure consists of stacked helical chains of octahedral metal(II) ions. Magnetic measurements show th